An assistant at surgery is a provider who actively assists the physician in charge of a case in performing a surgical procedure. A physician, nurse practitioner, physician assistant or clinical nurse specialist who is authorized to provide such services under state law can serve as an assistant at surgery.

Medicare considers advanced registered nurse practitioner (ARNP), physician assistant (PA), and clinical nurse specialist (CNS) as non-physician practitioners. Medicare does not recognize a registered nurse first assistant (RNFA) as a qualified Medicare provider.

To report services of an assistant surgeon, the following surgical modifiers should be appended:

• 80 — Assistant Surgeon: This modifier pertains to physician’s services only. A physician’s surgical assistant services may be identified by adding the modifier 80 to the usual procedure code. This modifier describes an assistant surgeon providing full assistance to the primary surgeon, and is not intended for use by non-physician providers.
• 81 — Assistant Surgeon: This modifier pertains to physician’s services only. Minimal surgical assistance may be identified by adding the modifier 81 to the usual procedure code, and describes an assistant surgeon providing minimal assistance to the primary surgeon. This modifier is not intended for use by non-physician providers.
Note: This modifier is used in the private insurance industry and is not commonly used in Medicare billing.
• 82 — Assistant surgeon (when a qualified resident surgeon is not available in a teaching facility): This modifier applies to physician’s services only. The unavailability of a qualified resident surgeon is a prerequisite for use of this modifier and the service must have been performed in a teaching facility. The circumstance explaining that a resident surgeon was not available must be documented in the medical record. This modifier is not intended for use by non-physician providers.
• AS — Non-physician provider as assistant at surgery: This modifier applies when the assistant at surgery services are provided by a PA, ARNP, or CNS.
Payment information
Medicare reimburses services rendered for assistant at surgery by a physician performing as a surgical assistant at 16 percent of the MPFS amount. Services rendered for assistant at surgery by non-physician providers are reimbursed at 85 percent of 16 percent (i.e., 13.6 percent) of the MPFS amount.
When reporting services provided by non-physician practitioners acting as assistants at surgery, append modifier AS to the procedure code used to report the surgeon’s service.
If a physician appends modifier AS to procedure codes for which he/she acted as assistant at surgery, these codes will be denied (see above for modifiers that should be used by physicians).

Medicare physician fee schedule database (MPFSDB) assistant at surgery payment indicators
The MPFSDB is a file layout that carriers and A/B MACs use to display the total fee schedule amount, related component parts, and payment policy indicators. The assistant at surgery payment indicator describes when assistant at surgery may be paid or not. Valid indicators are:

• 0 = Payment restriction for assistants at surgery applies to this procedure unless supporting documentation is submitted to establish medical necessity.
• 1 = Statutory payment restriction for assistants at surgery applies to this procedure. Assistant at surgery may not be paid.
• 2 = Payment restriction for assistants at surgery does not apply to this procedure. Assistant at surgery may be paid.
• 9 = Concept does not apply.
If multiple services are submitted with modifiers indicating assistants at surgery, each service is independently reviewed (based on the above-listed indicators) to determine payment.